I have my preference ( 1dx ) but as a pro you should be able to contact both CPS and NPS and try out some gear and really consider the focal length you use most of the time... prime, zooms etc etc and the lens offered by the brands. I dont think the D800 has the weather sealing you need, but it's not like the 1DX is waterproof either, but is considerable better sealed, as it should be.